The invention concerns a movable object carrying data to be read without contact or to be overwritten without contact by a reading/writing device having a main reading direction.
In the most varied areas of applications such as fabrication, maintenance, analysis, stock keeping etc. it is desired more and more to equip movable objects with automatically readable identification means. Such identification means is e.g. used for automatic identification of the objects. Automatically readable identification means are e.g. markings readable with optical means or electronically stored data.
Optical markings are e.g. bar codes. Reading of such optical identification means is carried out without contact, whereby a reading distance and a reading angle must be maintained within a given range and whereby the marking must be visible, i.e. not separated from the reading equipment by a non-transparent medium.
Electronically stored data is e.g. stored in a suitable integrated circuit which circuit is attached to the object to be identified. For reading the stored data, this kind of circuit is contacted by a reading device or by a probe of such a device or it comprises an antenna and the stored data are read without contact by a appropriately equipped reading device. Circuit, antenna and reading device can be designed such that the data which is stored in the circuit can not only be read by the device but can also be overwritten (reading/writing device) and also such that the energy required in the circuit for reading or overwriting is transmitted from the device to the circuit without contact such that no special source of energy (e.g. battery) is required for the circuit on the movable object.
In contrast to the optical markings, electronically stored data can take over a controlling function as well as an identifying function, i.e. with the help of such data suitably equipped devices can be triggered directly.
For data communication with contact, the reading/writing device and the object are to be brought into a precisely defined relative position. Data communication without contact is possible in more or less freely selectable relative positions of object and reading/writing device depending on the design of circuit, antenna and reading/writing device. However, in a system with a large freedom concerning the position of the reading/writing device it is more difficult or no longer possible without further means to restrict the data communication to one specific object or to functionally couple a locality with an object (for localizing objects and/or for control functions to be taken over by objects being present in one specific position).
An object of the invention is to provide objects carrying electronically stored data such that the data can be read and/or overwritten without contact, wherein a large freedom concerning relative positions of a reading/writing device and the object is to be guaranteed and whereby it is to be possible to note and to functionally use a present position of the object.
The inventive movable object comprises an integrated circuit in which data is electronically storable and an antenna. The antenna substantially consists of a conductive loop (antenna loop) which is closed by the integrated circuit and defines an antenna area. For a writing or reading process, the object is positioned relative to a reading/writing device with a main reading direction such that the main reading direction of the device penetrates the antenna area vertically or obliquely (is not arranged parallel to this area), whereby during the writing/reading process object and reading/writing device are stationary or move relative to each other.
The antenna loop or the antenna area respectively is designed and positioned on the object such that a reading/writing process carried out by a specific reading/writing device is possible for as many equivalent positions of the movable object as possible without having to change the main reading direction of the reading/writing device. This means that a substantially unchanged main reading direction penetrates the antenna area of the object regardless of the specific one of a plurality of equivalent positions the object is presently in. Equivalent positions of objects are to be understood as a plurality of positions in which the object can be found in a reading/writing locality for reasons not concerning the reading/writing process.
The conductive loop can be designed such that it is only closed for specific configurations of the object, i.e. that the data of an object can only be overwritten or read respectively as long as the object has one of these specific configurations.